Arrays of biological material have become a core technology used to advance studies in numerous fields. A variety of such arrays have been developed, including DNA microarrays, protein/antibody microarrays, and tissue microarrays indicating the broad appeal and utility of this approach. The explosion in popularity of arrays has led to an equally dazzling explosion of data that can be gathered from biological processes. Arrays have been used in studies on the nervous system, cancer, environmental toxicology, and reproductive biology. Microarrays may eventually produce personalized medical information for individual patients. These are just a few of the numerous applications for microarrays that have been published to date.
DNA arrays, in particular, have become an attractive means of studying biological processes. In these arrays, DNA fragments are positioned at high density on a solid support, such as on glass slides or on nylon membranes. To apply the DNA, robotics are used to “spot” or spray DNA on the surface at set intervals. The array therefore comprises a large number up to ˜100,000 with current technology) of individual spots of DNA located at discrete intervals on the slide. A competing technology that has also been heavily used are Affymetrix arrays, which use photolithography to synthesize DNA in situ on silicon wafers.
The explosion in popularity of such arrays has led to the introduction of numerous novel array methodologies, including new means of printing arrays (e.g. different means of depositing DNA on the array surface), novel array platforms (e.g. those not employing traditional glass or nylon based supports;), and array analysis packages (e.g. commercial or academic software).
It has become increasingly obvious, however, that current array technology, while still evolving, is limited by methodological and technological barriers that limit the sensitivity, and therefore the utility, of the technique. The utility is limited by a failure to achieve uniform deposition of materials on the array and a failure to eliminate non-specific hybridization to the array. The ability to improve either of these critical areas would greatly increase the utility and sensitivity of microarray techniques.